The central actions of angiotensin I, II, and III, and the possible roles of the angiotensins in the elevation of arterial blood pressure will be investigated in both anesthetized and awake cats and dogs. In addition, the effects of angiotensin I and II, administered via the cerebral lateral ventricles of anesthetized and awake cats on perpheral renin secretions will be investigated. Data obtained to date indicate that an increase in the levels of angiotensin I and/or angiotensin II in the cerebrospinal fluid markedly increases both systolic and diastolic blood pressure. The elevation in arterial blood pressure appears to be mainly due to an increase in peripheral resistance, especially that in the mesenteric and renal vascular beds. The above studies should identify mechanisms involved in the central pressor effects of angiotensin I and II and correlate the effects of increased concentrations of the angiotensins in the cerebrospinal fluid with sodium retention, peripheral blood pressure, urine production and sympathetic flow to the renal arteries. BIBLIOGRAPHIC REFERENCES: Vollmer, R. R. and Buckley, J. P., "Interaction of Angiotensin II with Central Adrenergic Receptors" in Central Actions of Angiotensin and Related Hormones, Pergamon Press, 1976 (in press). Jandhyala, B. S., Singh, S. and Buckley, J. P., "Further studies on Centrally Mediated Hemodynamic Effects of Angiotensin II in Anesthetized Cats" in Central Actions of Angiotensin aad Related Hormones, Pergamon Press, 1976 (in press).